The present invention relates to an applicator, especially for highly viscous materials, comprising a housing and a piston rod supported in the housing which upon actuation by an actuating element is displaced from an inactive position into a working position, i.e., upon movement in the working direction, is movable by passing two serially arranged jamming elements in the forward direction, whereby an actuator jamming element upon actuating the actuator element is jammed and displaced forwardly together with the piston rod and a locking jamming element is jammed by spring-loading into the rearward direction and supported at the housing.
Such an applicator for highly viscous materials, especially for dental filling materials, is, for example, known from German Offenlegungsschrift 36 07 384. This applicator comprises a pistol grip with a pressing element that dispenses the dental filling material via a drive mechanism with each actuation. When the cartridge with the dental filling material is empty, the piston rod can be released by a release rod and returned so that a new full cartridge can be inserted.
Dental filling materials, in general, must be exactly metered so that it is desirable that the amount of material dispensed upon actuation of the pressing element is constant. Especially, it is desired that the actuation will prevent further flowing of the pastelike or the highly viscous material, especially since this is frequently going hand in hand with contamination. In the solution known from German Offenlegungsschrift 36 07 384, for avoiding further unwanted oozing of the dental filling material from the dispensing opening, it is provided that upon actuation of the pressing element or actuating element, subsequently to the dispensing process, a pressure relief of the piston rod with a special relief lever is performed which is a unitary part of the actuating lever and acts on a locking jamming element.
It is disadvantageous in this apparatus that pressure relief can only be performed when the pressing element has completed its entire stroke. On the other hand, an operator, after completed pressing of the desired amount, has the tendency not to apply any further force in order to complete the stroke of the pressing element, especially since the desired dispensing effect has already been achieved. Accordingly, it is not ensured that unwanted dispensing can be prevented with this apparatus.
It is therefore an object of the present invention to provide an applicator of the aforementioned kind which reliably prevents unwanted dissension (oozing) of the material to be applied from the dispensing opening.